1. Field of the Invention
The present invention relates to power optimization of an optical disc apparatus and more particularly to power optimization when data is recorded on a recordable optical disc.
2. Description of the Related Art
OPC (Optimum Power Control) is a publicly known technology for optimizing recording power when data is recorded on an optical disc. With OPC, test data is recorded on a predetermined area PCA of an optical disc at various power levels. Each set of test data recorded at a different recording power is then reproduced so as to determine the optimum power by selecting the recording power at which jitter or error rate becomes minimum, or the power level at which jitter or error rate becomes less than or equal to a threshold value.
An alternate method for determining the optimum recording power without performing test recording has also been known. According to this alternate method, data on an optimum recording power prestored in a control data zone of an optical disc is initially retrieved and then recording under the retrieved optimum recording power is performed on DVD-RAM or the like.
A method using data concerning the optimum recording power previously recorded on the control data zone of the optical disc, however, is problematic in that data recording under the optimum recording power is not always achieved optimally when a combination of an optical disc and an optical disc driver (optical disc apparatus) is changed. That is, because optical properties such as optical pickup and the like will vary among different optical disc apparatuses, an optimum recording power obtained by one optical disc apparatus under a certain standard is not always optimum for another optical disc apparatus. This method has another problem in that it is incapable of supporting variations in optimum recording power resulting from changes in recording characteristics due to degradation of the optical disc by aging.
Although these problems can be avoided by using OPC to determine the optimum recording power, with such a composite method there is a problem that it cannot be known whether or not the determined recording power is capable of providing sufficient margin of recording conditions. This uncertainty of recording margin raises the possibility of recording instability. As a solution to secure recording margin when optimum recording power is determined by OPC, it is possible to select a recording power higher than the needed optimum recording power. However, excessively increasing the recording power may decrease the number of recordings that can be made on a disk, leading to a durability problem.